Comparison of effects of excess dietary protein, methionine or
chloride on acid-base balance and on cysteine catabolism to taurine
versus sulfate.
Bella, Deborah L., and Martha H. Stipanuk.
Division of Nutritional Sciences, Cornell University, Ithaca, NY
14853
APStracts 2:0136E, 1995.
Metabolism of cysteine to sulfate results in production of H+, whereas
metabolism of cysteine to taurine does not. Rats were fed a basal low
protein diet or a diet with excess protein, methionine or chloride
for 2-3 weeks, and effects of these treatments on acid-base
homeostasis and on cysteine metabolism were determined. Hepatocytes
from rats fed diets with excess methionine, but not from rats fed
diets with excess protein or chloride, catabolized a high proportion
of cysteine to taurine (32% versus 4-7% for other groups), and intact
rats fed excess methionine excreted more sulfur as taurine (51% of
total sulfur versus 1-6% for other groups). The formation of taurine
versus sulfate as the end product of cysteine catabolism provides a
metabolic compensation that minimizes the acid load in rats fed
excess sulfur amino acids. However, increased production of taurine
versus sulfate is not a general adaptive response to acidogenic
diets.
Received 5 April 1995; accepted in final form 15 June 1995.
APS Manuscript Number E163-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.